BCB client app connecting to PostgreSQL database

Hi,
I am preparing to develop a 2-tiered database applicaton for my sister who is in the Head Hunting industry. Currently there are 5 employees accessing/editing the same database on their own personal computers, without any form of client/server model yet. Basically everyone keeps track of their own copy of database.
My intention is to use BCB5 to develop the client application to be installed on all employees' PC and install PostgreSQL on a server, running either WIN2K or Linux which I have not decided yet, to host the database. As a result, all her employees can access the same database at the same time.
I am sure there are a lot of developers have already developed their client apps through Delphi/BCB connecting databases hosted by MySQL, but what about PostgreSQL?
I have seen some reviews/comparisons between MySQL and PostgreSQL, and it seems PostgreSQL possess some additional strengths over MySQL that I deem important, hence I have decided to go with PostgreSQL. I hope I am not flaming MySQL supporters here
In addition, which OS (WIN2K or Linux) would be more ideal for my server hosting PostgreSQL database, and to support client app that will be running from Windows-based PC?

Have you considered Interbase (or its free version, Firebird) for the engine? The reason I ask is because it was acquired and maintained by Borland and thus their tools have very good support for it. They later released Interbase source code and Firebird was derived from the released source. You can use PostGres, but you might need to use an ODBC connection to hook to it, whereas Interbase/firebird will use native drivers. Also, Interbase/firebird has the sort of things that good relational database engines (postgres, mssql, sybase etc.) do, such as transactions, stored procedures, triggers etc. and has been used in large corporate environments as well (Boeing, Motorola, Nokia and a large US stock exchange are well known examples).